1. Technical Field
The present invention is directed to electro-stimulators and a pacemaker electrode, and specifically for the removal of implanted endocardial pacemaker electrodes from a patient""s heart and the venous paths thereto.
2. Description of the Related Art
Various types of pacemaker leads and their electrodes are used in different chambers of the heart, including the right ventricle, right atrial appendage, the atrium and the coronary sinus. The leads provide an electrical pathway between a pulse generator, connected to the proximal end of the lead, and the electrode connected to the distal end of the lead. The electrode tip is often placed in contact with the endocardial or myocardial tissue by passage through a venous access, such as the subclavian vein or one of its tributaries, which leads to the endocardial surface of the heart chambers. The electrode tip of many available leads include flexible tines, wedges or finger-like projections which project radially outward to help prevent dislodgment of the lead tip from the cardiac tissue. Once an endocardial lead is implanted within a heart chamber, the bodys reaction to its presence furthers its fixation within the heart. Shortly after placement, blood clots form about the electrode due to enzymes released in response to the irritation of the cardial tissue caused by the electrode tip. Over time, fibrous scar tissue eventually forms over the distal end, usually in three to six months. Electrical pulses emitted by the pacemaker travel through the pacemaker lead, to the electrode and into the heart muscle and stimulate the heart to restore healthy heart rhythms for patient""s whose hearts are beating irregularly.
Leads and electrode tips occasionally malfunction, due to a variety of reasons, including lead block, insulation breaks, breakage of the inner helical coil conductor, etc. In addition, it is sometimes desirable to electronically stimulate different portions of the heart than that being stimulated with electrode tips already in place. Due to these and other factors, a considerable number of patients may eventually have more than one, and sometimes as many as four or five, unused leads and electrode tips in their venous systems and heart. These unused leads and electrode tips often develop complications, such as valvular regurgitation, infection, septicemia, or endocarditis. In addition, unused leads may entangle over time, thereby increasing the likelihood of blood clot formation, which may embolize to the lung and produce severe complications or even fatality. Further, the presence of unused leads in the venous pathway and inside the heart may cause considerable difficulty in the positioning and attachment of new endocardial leads and electrode tips in the heart.
Conventional techniques for removing unused pacemaker leads and electrode tips are associated with serious risks. Standard mechanical traction and, more often, intravascular mechanical countertraction are the methods most commonly used at present. External mechanical traction involves grasping the proximal end of the lead and pulling. This process is repeated daily and usually a few millimeters of the lead are removed from the patient each day, with progress monitored by chest radiography. Internal mechanical traction is accomplished by exerting traction (manual or sustained) on the lead via a snare, forceps or other retrieval catheter that has grasped the lead within the venous system. These techniques, however, can cause disruption of the heart wall prior to release of the affixed lead tip, causing fatality, or other complications, such as lead breakage with subsequent migration, myocardial avulsion or avulsion of a tricuspid valve leaflet. Moreover, lead and electrode tip removal may further be prevented by a channel of fibrotic scar tissue and endothelium surrounding the outer surface of the lead body or insulator sleeve at least part way along the venous pathway. Such channel scar tissue inhibits withdrawal of the lead and electrode tip because they are encased within the scar tissue.
Conventional electrosurgery methods have not been successful in removing pacemaker leads. One of the factors which appears to create the greatest impediment to electrosurgical removal of pacemaker leads is scar tissue. Scar tissue exhibits much lower thermal conductivity and electrical conductivity than normal (e.g., myocardial) tissue. Since conventional electrosurgery generally relies on the conduction of electrical currents through the target tissue being cut or vaporized, conventional electrosurgery has failed to remove this scar tissue. In fact, previous attempts to use conventional electrosurgery methods to remove pacemaker leads have resulted in current flow and thermal effects in the xe2x80x9chealthyxe2x80x9d tissue surrounding the scar tissue mass, but not in the scar tissue mass itself. As a result, the targeted scar tissue was not affected and the lead was not removable.
What is needed is an apparatus for removing unused pacemaker leads that can relatively quickly and easily cut through the fibrotic scar tissue and endothelium surrounding the outer surface of the lead body and electrode tip and does not require additional apparatus for removal except the lead and electrode tip itself.
It is an object of the present invention to provide a lead body and electrode tip that is relatively easy to insert
It is another object of the present invention to provide a lead body and electrode tip that can be removed without being associated with serious risks.
It is yet another object of the present invention to provide a lead tip that upon removal can relatively quickly and easily cut through the fibrotic scar tissue and endothelium surrounding the outer surface of the lead body and electrode tip.
The above objects are achieved by providing an extractable endocardial tip for an electrode of an electrical stimulator having a lead body with a front end for positioning the electrode within a desired area and a back end for connecting to an electrical source. The lead body may have convexities or concavities to increase the contact surface and improve conductivity. At least one fin protrudes from the lead body. The fin has an anterior leading edge and a posterior receding edge wherein at least a portion of the posterior receding edge is serrated to form a cutting surface. The serrated edge is relatively sharp such that when the electrode is pulled, the serrated edge of the fin cuts through any fibrous scar tissue or any other inhibiting material that surrounds the electrode to facilitate the relatively easy withdraw of the electrode from the heart.
Additional objects, features and advantages will be apparent in the written description which follows.